Transcatheter device and minimally invasive method for constricting and adjusting blood flow through a blood vessel

ABSTRACT

A pulmonary artery flow restrictor system includes a funnel shaped membrane with a proximal base and a restrictive distal opening which is stretchable to larger sizes. A self-expanding frame is attached to the proximal base of the membrane for securing the membrane within the pulmonary artery.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/420,772 filed Jan. 31, 2017 and claims benefit of and priority toU.S. Provisional Application Ser. No. 62/289,402 filed Feb. 1, 2016,under 35 U.S.C. § 119, 120, 363, 365, and 37 C.F.R. § 1.55 and § 1.78,which are incorporated herein by this reference.

GOVERNMENT RIGHTS

This invention was made with government support under HHSN268201400058C,awarded by the National institutes of Health. The government has certainrights in the invention.

FIELD OF THE INVENTION

This invention relates to a pulmonary artery restriction device and aminimally invasive method for constricting and adjusting blood flowthrough a blood vessel.

BACKGROUND OF THE INVENTION

Congenital heart disease (CHD) refers to the various malformations ofthe heart and surrounding vessels that occur prior to birth. Almost 1%of children are born with some form of significant CHD. CHD remains aleading cause of infant death in the United States. Many infants withCHD develop exuberant blood flow to their lungs that, if left untreated,may result in overwhelming congestive heart failure and death. Forexample, in ventricular septal defect (VSD), the most common type of CHDoccurring in about 37% of cases, holes in the septum allows oxygen richblood entering into the left ventricle from the lungs to leak out to theright ventricle and escape out the pulmonary artery instead of out theaorta and to the rest of the body. When, however, complete surgicalrepair in infancy is not possible or not ideal, it becomes imperativethat the pulmonary blood flow be restricted in order to allow the infantto thrive to an age where repair is feasible. The current approach formany of these children is to surgically limit their pulmonary bloodflow. This can be accomplished by cinching down on the main or branchpulmonary arteries with a band (pulmonary artery band) or by completelyremoving the natural flow to the lungs and replacing it with acontrolled source of blood flow through a Gortex shunt or surgicalconduit. See published U.S. Application No. 2014/0236211 and U.S. Pat.No. 5,662,711 both incorporated herein by this reference.

Although effective in controlling pulmonary blood flow, the pulmonaryartery band results in distortion of the pulmonary arteries which cannegatively impact future surgical intervention. In addition, thepulmonary artery band can only be adjusted through additional surgery.Similarly, placement of a surgical shunt or conduit may result indistortion of the pulmonary arteries. Such artificial connections havethe potential for thrombosis, distortion and occlusion, which may havefatal consequences. See also U.S. Pat. No. 6,638,257 and WO 2015/114471both incorporated herein by this reference.

SUMMARY OF THE INVENTION

Featured is a pulmonary artery flow restrictor system comprising afunnel shaped membrane with a proximal base and a restrictive distalopening which is stretchable to larger sizes and a self-expanding frameattached to the proximal base of the membrane for securing the membranewithin the pulmonary artery.

In one example, the frame includes arms extending upward over themembrane distal opening. The funnel shaped membrane may be made of apolymer, for example, polytetrafluoroethylene (ePTFE). The frame may bemade of a shape memory alloy, for example, Nitinol.

The frame may include a stent like structure with a series of spacedupper and lower apexes. Preferably, the spaced lower apexes are securedto the proximal base of the membrane. In one example, the frame furtherincludes a plurality of bent anchoring arms extending upwardly over themembrane distal opening each formed from members extending from adjacentframe upper apexes. The arms may cross above the membrane distalopening. The pulmonary artery flow restrictor may further include one ormore flexible lines connected to the frame for collapsing the frame.

The pulmonary artery flow restrictor system may further include atranscatheter device for delivering the membrane and frame into thepulmonary artery. In one example, the transcatheter device includes aninner lumen about a guide wire and a retractable lumen retractablerelative to the inner lumen. The frame may be removably attached to theinner lumen, using, for example, pins attached to the inner lumen andframe eyelets receiving said pins therethrough.

Also featured is a pulmonary artery flow restrictor comprising amembrane including a restrictive opening. The membrane is made of amaterial which is irreversibly stretchable to larger sizes by a ballooncatheter to vary the size of the restrictive opening. A self-expandingframe is attached to the membrane for securing the membrane within thepulmonary artery. Preferably the frame includes arms extending upwardover the membrane restrictive opening. The membrane is preferably madeof a polymer such as polytetrafluoroethylene (ePTFE).

The development of a percutaneous intravascular pulmonary arteryresistor would avoid the complications associated with theseconventional techniques and have the potential for non-surgicaladjustment over time to accommodate for growth. Such a device wouldgreatly impact the treatment approach to many children with congenitalheart disease. In addition, it would provide a minimally invasiveapproach for palliation of children in parts of the world where accessto surgery is limited or nonexistent. Such an approach ultimately relieson surgery for definitive treatment in these children, but it replaces aseries of operations with a single operation that can be planned andscheduled well in advance.

The subject invention, however, in other embodiments, need not achieveall these objectives and the claims hereof should not be limited tostructures or methods capable of achieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled inthe art from the following description of a preferred embodiment and theaccompanying drawings, in which:

FIG. 1 a schematic view showing an example of a pulmonary artery flowresistor in accordance with the invention;

FIG. 2 is a schematic view showing the resistor of FIG. 1 deployed andin place within the pulmonary artery;

FIG. 3 is a schematic view of a transcatheter device for delivery apulmonary resistor into the pulmonary artery;

FIGS. 4A 4H are schematic views showing the delivery of the pulmonaryartery flow resistor into the pulmonary artery; and

FIG. 5 is a schematic view showing another example of a pulmonary arteryflow resistor.

DETAILED DESCRIPTION OF THE INVENTION

Aside from the preferred embodiment or embodiments disclosed below, thisinvention is capable of other embodiments and of being practiced orbeing carried out in various ways. Thus, it is to be understood that theinvention is not limited in its application to the details ofconstruction and the arrangements of components set forth in thefollowing description or illustrated in the drawings. If only oneembodiment is described herein, the claims hereof are not to be limitedto that embodiment. Moreover, the claims hereof are not to be readrestrictively unless there is clear and convincing evidence manifestinga certain exclusion, restriction, or disclaimer.

One or more embodiments of the transcatheter device and minimallyinvasive method for constricting and adjusting blood flow through ablood vessel of this invention provides a minimally invasive surgery(MIS) device which can be implanted within the main pulmonary artery inorder to elevate flow resistance to palliate the patient's CHD symptomsand move toward systemic flow. The device includes a self-expandingmetal frame or skeleton which constrains the device radially and axiallyattached to a balloon-expandable membrane, also referred to herein as apulmonary artery resistor, that interacts with, the blood flow andprovides flow constriction. The pulmonary artery resistor facilitatesMIS intervention for modification of flow resistance.

The device may be deployed minimally invasively via catheter by acardiac surgeon. As initially configured, the pulmonary artery resistormay provide the highest level of flow resistance possible. The highestlevel resistance would palliate patients with the most severe CHDsymptoms, such as multiple and large septal tears the highest spectrumCHD cases. However, in those cases where less restriction is desired,the surgeon may use a balloon catheter of the desired size toincrementally expand the size of the resistor in situ. An adequate sizedballoon is chosen and delivered over a guidewire to a location insidethe resistor. The balloon is then dilated to expand the resistor. Theballoon is then deflated and finally removed. This cycle ensures thatthe adjustment is performed quickly since a fully expanded balloon inthe middle of the main pulmonary artery (Main PA) may cause an acutespike in pulmonary pressure and stress on the heart. Evaluation of thesufficiency of the resistance change provided by the pulmonary arteryresistor is obtained after the dilation balloon has performed theexpansion task and is fully removed from the patient, while theguidewire and femoral introducer catheter remain in place. A surgeon mayincrementally alter the resistance further by stepping up the size ofthe balloon and repeating the dilation procedure. The expansion cyclescontinue until a satisfactory pulmonary arterial pressure is reachedwhile adequate oxygenated blood flow to the aorta is also satisfactory.

Future follow on MIS procedures to reduce resistance may be periodicallynecessary to maintain desired apportionment of blood flow between thelungs and the remainder of the body as the patient grows. The minimallyinvasive procedure to correct the flow resistance should reduce oreliminate post-surgery recovery time in an intensive care unit andhospital stay duration when compared to conventional pulmonary arterybanding which requires open surgery. The pulmonary artery resistorincorporates the flow constriction geometry necessary to create thedesired flow without distorting the pulmonary artery wall.

In one embodiment, the frame of the resistor may be a tubular closed oropen celled lattice made out of a shape memory alloy such as nitinol.The frame may be plated in gold or other radiopaque material or alloy toimprove visibility inside the vessel. The frame may include eyelets withinserted radiopaque rivets that enhance visibility for the surgeon. Inone embodiment the frame preferably includes at least two crossing arms,which preferably extend beyond its tubular radius. The arms may includeslots for improved adhesion to the vasculature walls. The distal ends ofthe arms may feature tips that have an increased surface area and abackwards bend, essentially forming feet that reduce the contactpressure against the vessel wall. The arms may be tied together in thecenter to prevent the frame from collapsing under high pressure.

The resistor membrane may be a 2D annular shape or an annular shapestretched along the third axis forming a conical tube or funnel. Themembrane may be made of an inelastic material that retains its new shapeafter deformation by the balloon as described above. The material may bewoven or otherwise structured in such a way that the membranepreferentially stretches in the radial direction while minimizingforeshortening. The material may be an expanded polytetrafluoroethylene(ePTFE) or similar type material. The membrane may be attached to theframe chemically such as an adhesive bond, mechanically such asstitching, hook and loop, thermal bonding or related technology. Themembrane may be extruded, wrapped, or otherwise formed separately fromthe frame and then attached in a post process. The membrane may also beformed directly on the frame via sputtering, wrapping, or other means.The expandable membrane may be attached on the proximal side of thedevice such that in the conical configuration the narrow end of thefunnel extends distally down the center of the frame.

The resistor may be deployed through a transcatheter procedure by whichthe device is collapsed between an inner guidewire lumen and outersheath lumen. In one embodiment, there may include two or moreproximally located eyelets on the frame which may extend axially beyondthe main body of the frame to interact with pins, hooks, recesses, orsome other attachment mechanism attached to the guidewire lumen. Whenthe frame is collapsed inside the catheter, with such an attachmentmechanism engaged, the mechanism constrains the axial and rotationalmotion of the frame such that any motion of the attachment devicetranslates into corresponding motion by the frame. This link may be usedfor ejection of the device out the distal end of the deploymentcatheter, for axially repositioning or rotating a semi-deployed device,or for re-sheathing a semi-deployed device.

FIG. 1 shows an example of a pulmonary artery flow resistor 10 includingfunnel shaped membrane 12 and self expanding frame 14. Membrane 12 hasproximal base 16 having a wide opening 17 (e.g., with a diameter ofbetween 10 and 18 mm) and a distal narrow opening or spout 18 (e.g.,having a diameter of between 0.5 and 6 mm). Preferably, frame 14 issecured to the base 16 of the membrane. In one example, base 16 was 14mm in diameter and restricted opening was 2 mm in diameter.

The membrane functions to resist blood flow through the pulmonary artery20, FIG. 2 since, when the flow resistor is in place in the pulmonaryartery 20, blood is restricted to only flow out distal narrow opening 18of membrane 12 since base 16 is urged against the inner wall of theartery. Frame 14 functions to retain membrane 12 in place in thepulmonary artery. Also, using a balloon catheter, the distal narrowopening 18 of membrane 12 can be enlarged in diameter by placing aballoon catheter inside opening 18 and expanding the balloon catheterwhereupon the material of the membrane in the area of opening 18stretches via the balloon catheter and retains its new, now largerdiameter. Thus, preferably, membrane 12 is made ofpolytetrafluoroethylene (ePTFE) or similar type polymer materialtypically between 0.3 thousandths of an inch and 3 thousandths of aninch thick. Other polymers may be used.

Frame 14 may be made of a shape memory alloy such as Nitinol. Frame 14may further include inwardly bent arms 22 a and 22 b extending upwardover membrane 12 and crossing above restricted opening 18 as shown inFIGS. 1 and 2. The arms may each extend into a branch of the pulmonaryartery as shown. The arms 22 a, 22 b have a large surface area to reducepressure on the pulmonary artery wall and function to anchor membrane 12in place against the normal blood flow.

As shown in FIGS. 1-2, frame 14 is a stent like in structure and beingself expanding it expands the membrane 12 and maintains contact withpulmonary artery wall even as the pulmonary artery grows in size.

Preferably, frame 14 includes circumferential lower spaced apexes 30 a,30 b, 30 c and the like and upper spaced apexes 32 a, 32 b, 32 c, andthe like each between adjacent lower apexes. The lower apexes may besecured to the proximal base 16 of membrane 12. Arms 22 a, 22 b mayinclude members extending from select upper apexes of the frame. So, forexample, arm 22 b includes member 34 a extending from apex 32 a andmember 34 b extending from adjacent apex 32 b. Crossing arms 22 a, 22 bmay be include downwardly bent distal eyelet tips 36 a, 36 b,respectively. Furthermore, lower apexes 30 a, 30 b, 30 c, and the likemay include eyelets 38 a, 38 b, and 38 c, and the like, respectively.Eyelet 38 a and the eyelet directly across from it may be slightlyenlarged and constitute deployment eyelets which fit over deploymentpins associated with a deployment device. The other eyelets (e.g., 38 b,38 c, and the like) may be used to secure the frame 14 to be base ofmember 12. The entire frame including the arms may be formed by cuttinga single thin tube of Nitinol which is then expanded on a mandrel andthen heat treated so that it naturally retains this expanded shape.Radiopaque stripes 15 a, 15 b may be included (printed on or adhered to)on membrane 12 to enable visualization of the membrane during deploymentinto the pulmonary artery. Frame 14 may include a radiopaque coating toenable visualization of the frame during deployment into the pulmonaryartery. In some examples, the flow resistor reduces the effectivediameter of the pulmonary artery to 2 mm, a diameter which can bechanged by using a balloon catheter to expand the flow resistor. Theflow resistor may provide a maximum pressure drop of 40-50 mm Hg in thepulmonary artery and resist the blood flow rate to a maximum of 1.5-2L/min. If the membrane is fully expanded, the flow resistor wouldproduce no pressure drop and no flow rate reduction. In testing, theflow restrictor shown in FIG. 1 could be collapsed down into a 2 mmdiameter package and then expanded such that base 16 and frame 14 were13 mm-14 mm in diameter (or equal to the vessel diameter). The height ofthe membrane may be 8-16 mm. The frame may be 5-15 mm (from upper apexto lower apex) and the arms may be 15-30 mm long.

The system may further include transcatheter device 60, FIG. 3 fordelivering the membrane and the frame into the pulmonary artery. Thedelivery device preferably includes inner braided guide wire lumen aboutguide wire 65 and retractile lumen 66 (e.g., 3-5 Fr) which isretractable relative to inner lumen 62 and flared at its tip (to, e.g.,5-9 Fr) forming a garage section. The frame is releasably attached tothe inner lumen, for example, by placing opposing deployment eyelets onpins 68 a, 68 b. Thus the frame and the membrane are collapsed andreside between lumen 66 and lumen 62. An outer support sheath 70 mayalso be provided. Braided guide wire lumen 62 may be thinned out justbefore a garage section giving maximum space between the garage sectionand guide wire lumen 62 in order to fit the restrictor device. The tipof the transcatheter device and the deployment pins 68 a, 68 b areattached to the thinned portion of guide wire lumen 62. The outer mostlumen 70 serves to reduce friction for the retractile lumen 66 as itretracts relative to outer lumen 70. Outer lumen 70 terminates beforethe garage section giving space for the translation. The retractilesheath 66 slides along the lubricious outer lumen inner liner ratherthan along the vessel walls.

FIG. 4A shows catheter 60 following the guide wire 20 to the artery. InFIG. 4B the catheter continues past the valve to just beyond the splitin the pulmonary artery. In FIG. 4C the lumen 66 is pulled back toreveal the arms of the restrictor frame. In FIG. 4D the hymen 66 ispulled hack more until the arms begin to separate and in FIG. 4E thecatheter is gradually pushed forward keeping the outer sheath hack. Theinner lumen 62 is then advanced, FIG. 4F until the deployment pins reachthe end of the sheath and in FIG. 4G the lumen 66 is pulled backallowing the frame and the membrane to spring into position. In FIG. 4H,the catheter and the guide wire are removed leaving the flow restrictorin place.

FIG. 5 shows a design where one or more flexible lines (e.g., sutures)80 are connected to frame 14 for collapsing the frame and removing theframe and the membrane 12 from the pulmonary artery 20. As shown in theexample of FIG. 5 a suture 80 a, 80 b, 80 c are each secured to thelower apexes 38 a, 38 b, 38 c, respectively of frame 14 to form a webwith a hook, loop, hall, knot, or other feature 82 tying the other endof all the sutures together in the center. This feature 82 may be snaredby a standard transcatheter snare. Also in this embodiment, arms 22 a,22 b may be flared members in a light bulb shape as shown with two orthree arms intersecting in the center where they are sutured together asshown as 84. The suture keeps the arms in place and acts as a hingeallowing the arms to collapse into the outer lumen during deployment orduring retrieval. The light bulb shape of the arms fit into the T of theartery. A snare may be guided through an outer lumen to grab ontofeature 82 and then pulled hack into the outer lumen whereupon frame 14collapses by the force on sutures 80.

Although specific features of the invention are shown in some drawingsand not in others, this is for convenience only as each feature may becombined with any or all of the other features in accordance with theinvention. The words “including”, “comprising”, “having”, and “with” asused herein are to be interpreted broadly and comprehensively and arenot limited to any physical interconnection. Moreover, any embodimentsdisclosed in the subject application are not to be taken as the onlypossible embodiments.

In addition, any amendment presented during the prosecution of thepatent application for this patent is not a disclaimer of any claimelement presented in the application as filed: those skilled in the artcannot reasonably be expected to draft a claim that would literallyencompass all possible equivalents, many equivalents will beunforeseeable at the time of the amendment and are beyond a fairinterpretation of what is to be surrendered (if anything), the rationaleunderlying the amendment may bear no more than a tangential relation tomany equivalents, and/or there are many other reasons the applicantcannot be expected to describe certain insubstantial substitutes for anyclaim element amended.

Other embodiments will occur to those skilled in the art and are withinthe following claims.

What is claimed is:
 1. A pulmonary artery flow restrictor systemcomprising: a funnel-shaped membrane for installation in an artery andincluding: a wide area base opening to receive arterial blood flow, anda distal narrower area spout to restrict the arterial blood flowtherethrough to a predetermined blood flow rate; and a self-expandingstent structure associated with the membrane to support the membrane inthe artery and spaced arms extending upwardly and over the funnel-shapedmembrane distal narrower area spout.
 2. The system of claim 1 in whichthe funnel-shaped membrane is made of an inelastic material so that ifthe distal narrower area spout is expanded it retains its expandedshape.
 3. The system of claim 1 in which the wide area base opening isabout 10-18 mm in diameter and the distal narrower area spout is about0.5-6 mm in diameter.
 4. The system of claim 1 in which the spaced armsare integral with the self-expanding stent structure.
 5. The system ofclaim 1 in which the funnel shaped membrane is made of a polymer.
 6. Thesystem of claim 5 in which said polymer is polytetrafluoroethylene(ePTFE).
 7. The system of claim 1 in which the self expanding stentstructure is made of a shape memory alloy.
 8. The system of claim 7 inwhich said shape memory alloy is Nitinol.
 9. The system of claim 1 inwhich the self expanding stent structure includes a wire bent to form aseries of spaced lower apexes and a series of spaced upper apexes. 10.The system of claim 9 in which the spaced lower apexes are secured tothe base of the funnel shaped membrane.
 11. The system of claim 1further including one or more flexible lines connected to the selfexpanding stent structure for collapsing the self expanding stentstructure.
 12. The system of claim 1 further including a transcatheterdevice for delivering the membrane and self expanding stent structureinto the pulmonary artery.
 13. The system of claim 12 in which thetranscatheter device includes an inner lumen about a guide wire and aretractable lumen retractable relative to the inner lumen.
 14. Thesystem of claim 13 in which the self expanding stent structure isremovably attached to the inner lumen.
 15. The system of claim 14 inwhich there are pins attached to the inner lumen and the self expandingstent structure includes eyelets receiving said pins therethrough. 16.The system of claim 1 in which the predetermined blood flow rate is1.5-2 L/min.